FIGS. 9, 10A and 10B illustrate a known chain transmission 500 which includes a roller chain 510 in which pairs of inner link plates 511 and pairs of outer link plates 512 are connected in an alternating, overlapping arrangement by connecting pins 513. In the known chain transmission, a sprocket 520, having a plurality of teeth 523, is engaged with the roller chain 510, which is wrapped partway around the sprocket. The teeth of the sprocket all have the same face width, which is only slightly less than the distance between an opposed pair of the inner link plates of the chain. The known chain transmission is described in Japanese Utility Model Publication No. H7-49101.
When a sprocket tooth 523 engages a roller 515 of the roller chain 510, the sprocket tooth enters the space between a pair of the inner link plates 511. Because there is only a small clearance between the tooth and the inner link plates, friction between the sides 523s of a sprocket tooth 523 and inner sides 511s of the inner link plates 511 adversely affects the efficiency of the chain transmission.
If the chain transmission is constructed so that there is a larger clearance between the sides of the sprocket teeth and the inner sides of the link plates, side slip or meandering of the chain 510 can readily occur while the chain transmission is operated. Therefore, as the sprocket teeth 523, all of which have the same face width, are sequentially inserted between a pair of the inner link plates 511, contact between the sprocket teeth and the link plates of the chain generates an undesirable contact sound.
I have conducted intensive research with the objective of addressing the aforementioned problems. This research focused on the conditions under which the outer side surfaces 523s of sprocket teeth 523 having the same face width contact the inner side surfaces 511s of the inner link plates 511 of a roller chain. I found that this type of chain transmission generates a periodic sound the frequency of which is the product of the rate of rotation of the sprocket and the number of sprocket teeth. I addressed the problems on the basis of this finding.
An object of the invention to provide a sprocket and a chain transmission using the same, in which contact resistance between the outer sides of the sprocket teeth and the inner sides of inner plates of a chain is reduced, the periodic sound generated is reduced, and a stable running path of the chain is maintained.